Exotic 3D Hierarchical ZnO-Ag Hybrids as Recyclable Surface-Enhanced Raman Scattering Substrates for Multifold Organic Pollutant Detection

Recyclable and sensitive surface-enhanced Raman scattering (SERS) sensors for the detection of a variety of organic pollutants were fabricated from 3D hierarchical ZnO-Ag hybrids, which were synthesized by an efficient and green approach. The ZnO nanostructure could be controlled by applying a facile organic-chemical-assisted hydrothermal method. The obtained structures were then decorated with different-sized Ag nanoparticles (Ag NPs) on their side surfaces and top ends to construct 3D hierarchical ZnO-Ag nanocomposites for use as multifunctional SERS substrates. The obtained SERS sensor manifested a high sensitivity to rhodamine 6G (R6G) at a low concentration of 1x10(-13) M and a detection limit as low as 5x10(-9) M for the organic herbicide 4-chlorophenol (4-CP). Moreover, because of the good, stable photocatalytic properties of this exotic 3D hierarchical structure, the ZnO-Ag hybrids could self-clean under UV irradiation; this allowed repeatable SERS detection of many organic pollutants over more than three cycles with tolerable intensity attenuation. Finally, the unique repeatable detection of the organic dye R6G and the persistent organic pollutant (POP) 2,4-dichlorophenoxyacetic acid (2,4-D) demonstrates a new route to eliminate the single-use problem of traditional SERS substrates and suggests promising applications of such materials as real-time online sensors for organic pollutant detection.